Factors regulating the accumulation and spatial distribution of the emerging contaminant triclosan in the sediments of an urbanized estuary: Greenwich Bay, Rhode Island, USA.

Triclosan (TCS) is an antimicrobial compound being increasingly used in personal care products (PCPs) over the last 40 years, and as a result is present in wastewater treatment plant (WWTP) effluents. Widespread domestic use has resulted in environmental discharge of TCS, whose ecological consequences, especially in the marine environment, are poorly understood. Continuous discharge of wastewater effluent has resulted in the accumulation of PCPs such as TCS in coastal and estuarine sediments. The present study investigated whether WWTP effluent is the primary source of TCS within a small urbanized estuarine embayment that is supplied by a single domestic WWTP. Greenwich Bay, located within Narragansett Bay (RI, USA) contained dissolved water column TCS ranging between 0.5 and 7.4 ng L(-1), and surficial sediment concentrations ranging between <1 and 32 ng g(-1). Despite predictions, spatial distributions of TCS were not related to proximity to the WWTP outfall. Further, a Greenwich Bay-wide sediment TCS budget, estimated by spatial interpolation, suggested that annual accumulation rates exceeded the calculated annual discharge of TCS from the local WWTP. Contributors of TCS to Greenwich Bay include advection from upper Narragansett Bay, which receives effluent from several large WWTPs and contains TCS-contaminated sediments from past manufacturing activities. This study provides evidence that WWTP effluent is an important source of TCS. It also demonstrates that WWTP systems are important controls to mitigate environmental discharge of TCS and that TCS is sufficiently persistent in the environment. As a result, distant as well as local WWTP sources should be accounted for when considering management actions to limit environmental TCS exposure.